To troubleshoot Nginx and PHP-FPM issues you'd want to check the domain site's vhost access.log and error.log logs located within directory at /home/nginx/domains/yourdomain.com/logs. You can see a full overview at centminmod.com/configfiles.html

FAQ item 19 has more info on all Centmin Mod relevant log files locations and how to use tail command to view a sample of the entries.

Also post the contents of your site's nginx vhost http /usr/local/nginx/conf/conf.d/yourdomain.com.conf and/or /usr/local/nginx/conf/conf.d/yourdomain.com.ssl.conf in BBCODE CODE tags as outlined at How to use forum BBCODE code tags

I just copied the config from a vhost that was created using centminmod in a test server

so I think doing those commands will just result in not found errors

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if the test server has centmin mod and wp-cli command installed, you can still run the wp commands asked. If wp-cli isn't installed on test server but it's centmin mod based, just run addons/wpcli.sh to install wp-cli command first